Pump inlet pressurizing system



May 24, 1966 H. P. TYLER 3,252,419

PUMP INLET PRESSURIZING SYSTEM Filed Dec. 16, 1963 INVENTOR.

HENRY P. TYLER ATTORNEY.

United States Patent 3,252,419 PUMP INLET PRESSURIZING SYSTEM Henry P. Tyler, South Bend, Ind, assignor to The Bendix Corporation, South Bend, Ind., a corporation of Delaare Filed Dec. 16, 1963, Ser. No. 331,050 7 Claims. (Cl. 1032) This invention relates to a closed fluid control system having a fluid pressurizing pump means whose inlet is divided into low pressure and high pressure portions to insure equal inlet and discharge flow rates.

As those skilled in the art to which my invention relates will readily appreciate, cavitation within fluid pumps has long been a problem due to the difference of inlet and discharge flow rates. It has been attempted in the past to reduce this problem by providing a boost pump and/or high pressure accumulator to the inlet side of a fluid pressurizing mechanism. However, such systems have had complicated expensive structure that has created manufacturing problems.

It is therefore a principal object of my invention to solve this manufacturing problem and eliminate the problem of pump cavitation and decrease wear within a pump as well as increase the volumetric efficiency thereof.

More particular, it is a principal object of my invention to divide a pump inlet into two stages, namely, a low pressure inlet and a high pressure inlet to enable complete and adequate filling of the pump cylinders prior to pressurizing and discharging of fluid therefrom.

It is another object of my invention to provide a pump with a means for equalizing inlet and discharge flow rates.

It is a further object of my invention to provide a pump having a high pressure and low pressure inlet portion with an accumulator charging means for the low pressure inlet portion of the pump.

It is a further object to provide a closed fluid control system having an accumulator as a fluid reservoir with means to communicate the accumulator to a low pressure inlet portion of a two stage inlet of a fluid pressure producing mechanism.

A still further object of my invention is to provide a pump with an inlet and discharge fluid port insert divided into a two stage inlet and a single stage discharge, which port insert is adapted to allow leakage flow to a casing cavity and for thereturn of the leakage flow to the high pressure portion of the two stage inlet.

Further objects and advantages will be readily apparcut to those skilled in the art to which my invention relates from the following description of the drawings, in which:

FIGURE 1 is a schematic of a fluid control system in accordance. with principles of my invention; and

FIGURE 2 is a cross section of a port insert for a pump in accordance with the principles of my invention.

With reference to the schematic of FIGURE 1, I-show a housing 10 containing an annular accumulator chamber 12 and a central pump cavity 14. As seen the accumulator chamber 12 is provided internally with an annular rolling type diaphragm 16 biased by a spring 18 bearing on a spring retainer 20 backing up the diaphragm 16 to thereby divide the accumulator chamber into two variable volume chambers 22 and 24. To the rear of the housing 10 I have provided an accumulator charging valve 26 communicating with the chamber 24. As may be readily appreciated, access plates for repair and servicing of the accumulator chamber may be provided by using techniques within the skill of the art and, therefore, they are not deemed necessary for illustration and discussion in the general schematic of FIGURE 1.

Within the pump chamber or cavity 14, I have proice vided a rotor 28 driven by a shaft 30 that is supported by bearings 32 and 34 within both the housing 14} and a support member 36, which support member is positioned in the cavity 14 against an annular shoulder 38 by an end cap 40 that is held to the housing by bolts 42 to close the cavity 14. As seen, the supporting structure 36 also houses a pump control means consisting of a reference spring 44 and a pressure responsive piston 46 within respective chambers 48 and 50. Both the spring 44 and the piston 46 are provided with spherical bearing ends 52 and 54, respectively, that in turn abut a rear bearing face 56 of a movable control element 53. The movable control member 58 is pivotally held to the housing 10 by journal bearings in the plane normal to the cross section shown to allow pivoting of the member 58 or swash plate, as it is more commonly termed in the pump art,

about an axis normal to the axis of the shaft 30, as

shown. This will hold the cam plate 58 down. However, for another mounting for the swash plate 53 or cam plate, as it may also be termed, the readers attention is directed to a Patent No. 3,009,422 issued November 21, 1961, to the common assignee, that detailed a trunnion mounting for the cam plate on the shaft 30. With such a central trunnion mounting, the shoes 62 are urged by a spring (not shown) into contact with the cam plate 58.

As seen, the rotor 28 is abutting a port insert 66 that is provided with leakage openings 68 therethrough and is adapted, as will be explained hereinafter, to supply fluid from a low pressure inlet 70 and a high pressure inlet 72 to the rotor cylinders where it is pressurized and delivered to a discharge port 74.

As seen, the pump rotor 28 delivers fluid, pressurized fluid, to the discharge port 74 that is connected to a conduit '76 provided with a check valve 78 to prevent return 1 flow and which conduit 76 terminates in a fluid motor inlet 80. Thus the discharge pressure from the port 74 is allowed to enter a fluid motor 82 and operate same and thereafter return by way of a conduit 84 via a filtering mechanism 86, familiar to those skilled in the art, and a pressure regulating valve 88 to the high pressure inlet portion 72 of my port insert 66.

As seen, the inlet pressure regulating valve 88 contains a spring biased by-pass valve 90 which will allow by-pass of fluid from conduit 84 into a conduit 92 to remove excess fluid from the high pressure port 72. As seen, the conduit 92 opens into the accumulator variable volume chamber 22 from whence it is directed by means of a conduit 94 to the low pressure inlet port 70.

In order to control the pressure of the flow delivered 'by the rotor 28, I have provided a branch conduit 96 leading from the discharge flow conduit 76 through a filter mechanism 28 to a control manifold 100. The manifold 100 is connected to a servo valve 102 and a depressuring valve 104, such that the discharge pressure is directed to a variable volume chamber 106 and a control valve inlet port 108 in the servo valve 102 and a fluid pressure chamber 110 in the depressuring valve 104. The control valve 102 is also provided with a second variable volume chamber 112 and an exhaust port 114. The second variable volume chamber 112 is connected by a conduit 116 to an exhaust port 118 of the depressuring valve 104, which conduit 116 is provided with a branch conduit 120 that is connected to a port 122 of the servo valve 102 to provide reference case pressure to the control valve 102. The servo valve 102 is provided with a sleeve housing 124 that has radial openings matching the aforementioned inlet and exhaust ports. Within the housing 124 a spool valve 126 is reciprocably mounted having pressure responsive areas 128, 130 and 132 with a valve control land 134 interpositioned with respect to areas 130 and 132 to control communication of 2 cross sectional view of FIGURE 2.

inlet 108 and discharge 114. The pressure responsive area 132 is provided with a projection 136 that is adapted to cooperate with a spring retainer 138 for a spring 146 that is biased between a movable plug 142 sealingly mounted within the valve sleeve 124 and adjusted therein by an adjusting screw 144.

The depressuring valve 164 is constructed with a conical valve 146 adapted to reciprocate within a valve sleeve 148 and controlled in such reciprocation by connection with a plug 150, as by a link 152, which plug 150 is positioned within a solenoid body 154 by a solenoid coil 156 in opposition to a spring 158 whenever a switch 168 is closed to communicate an electrical source to the solenoid coil 156, as seen in FIGURE 1.

Depressurizing valve 104 during start is open and discharge pressure passes through 104 to area 130 of servo valve 102. This pressure is also acting on area 128. The respective passage 180 creates a pressure drop precluding discharge pressure from acting on the area 132. Thus, the effect of pressure on both areas 123 and 130 is to overcome the spring 140 to move the valve control land 134 to open discharge to conduit 182, as soon as pressure in the system reaches a depressurized level (i.e. something less than the 4200 psi. mentioned). From this point on, the pump will act as a variable delivery pump maintaining a relatively low discharge pressure.

Then when switch 169 is closed, solenoid coil 156 is actuated to close valve 146. This changes the effective area to actuate valve 194 from both 128 and 130 to only area 128. System pressure now builds up to the order of 4200 psi. and is maintained by servo valve 102.

After closing valve 148 to raise the pressure for the system, the pressure on area 130 is bled off through the aforementioned restrictive opening 180 to port 122 and thence to case or pump chamber 14. This will equalize pressures on areas 130 and 132 in that theyare bled to the chamber 14 so that pressure on 128 is biased against spring 149.

If desired, both the servo valve 102 and the depressuring valve 104 may be integrally associated with the housing 10, but for purposes of explanation and ease in illustration they are shown separate thereof.

The port insert 66 is shown in greater detail by the In detail, the port insert 66 comprises an outer shell 162 having an annular passage 164 that communicates with a plurality of radial leakage passages 68, aforementioned. Underlying the annular passage 164 is an intersection 166 having a plurality of kidney-shaped ports 170, 172 and 174 axially therethrough that are arranged to open to cylinders within the rotor 28 of FIGURE 1. These ports have been numbered to correspond with the low pressure inlet, high pressure inlet, and discharge ports 70, 72 and 74, respectively, in order to orient the reader of the specification. As is also seen in FIGURE 2, the port 172 is provided with a radial opening 176 arranged to communicate with a radial passage 178 in the shell 162 whereby case pressure may be communicated to port 172, which case pressure is a result of leakage flow between the port insert and rotor 28 that is communicated to cavity 14 by the openings 68 in the shell 162. Transition openings may be drilled or otherwise formed in member 166 between kidney-shaped ports 172 and 174 as shown in FIGURE 2.

In operation a motor or similar drive means is connected to the shaft 30 and the rotor 28 is rotated to discharge fluid to operate the motor 82, which fluid is then returned to the pressure regulator which is set to open at a predetermined pressure to by-pass fluid to the accumulator variable volume chamber 22. As the accumulator variable volume chamber 22 is openly connected to the low pressure inlet 70, the cylinders within the rotor 28 will be precharged to such an extent as to lessen the amount of fluid ingested by the high pressure port 72 to fill the cylinders.

Furthermore, the case leakage flow that is introduced via the passages 176 and 178 to the high pressure inlet 72 further reduces the capacity of the cylinders within the rotor 28.

It should also be noted that the branch conduit 120 between the depressuring valve 104 and the servo valve 102 is provided with a fixed orifice 180 for bleeding leakage flow from the valves and allow the depressuring valve to schedule discharge pressure flow for chamber 112, This discharge pressure will act on the area 130 in addition to the smaller area 128 to cause the spool 126 to move downwardly. As the spool 126 moves downwardly, as may be experienced in the above situation, or when the pressure in conduit 76 has exceeded the above mentioned value in the system it related to, the spool 126 opens the discharge port 114 to a conduit 182 that opens into the variable volumechamber 50 behind piston 46, to cause piston 46 to move outwardly out of the chamber 50 tilting the cam plate 58 to a position of creating lesser discharge pressure. As will be readily understood by those skilled in the art, the port insert 66, as seen in FIGURE 1, is rotated to enable a consolidated showing of pump and port detail.

A conduit 184 is arranged to communicate the branch and the chamber immediately under the pressure responsive area 132 to the case or pump cavity 14 to provide a reference to case pressure for area 132 that is always constant, so that discharge pressure is opposed by the spring 140.

In the above description I have disclosed in a general manner what I deem to be a practical and eflicient embodiment of my invention. It should be well understood, however, that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

I claim:

1. A means to pressurize an inlet of a pump to eliminate need for a boost pump in a fluid controlled system, said means comprising:

a fluid pressurizing means having a fluid delivery means including,

(a) a two-stage inlet having a high pressure portion and a low pressure portion, and (b) a fluid pressure discharge port;

a reservoir in fluid communication with said low pressure inlet portion;

a device to be operated by said fiuid pressurizing means which device is in fluid communication with the discharge port;

a conduit for returning fluid from said device operated by said fluid pressurizing means, which conduit is connected to said high pressure inlet port; and

a pressure regulating means in said conduit to by-pass fluid from said conduit to said reservoir to which said pressure regulating means is connected.

2. In a variable discharge pump a means to eliminate fluid cavitation which means comprises:

a port insert for said pump, said port insert having,

(a) a high pressure inlet portion, (b) a low pressure inlet portion, and (c) a discharge portion;

an accumulator for supplying a low pressure fluid to said low pressure inlet portion;

a conduit for supplying a high pressure fluid to said high pressure inlet portion; and

a pressure regulating means in said conduit and in fluid communication with said accumulator, which pressure regulating means is adapted to by-pass fluid to said accumulator that is in excess of the capacity of said high pressure inlet portion.

3. In a variable discharge pump, a'means to eliminate 5 fluid cavitation in accordance with claim 2 and further comprising:

a plurality of openings in said port insert to permit leakage fiow from said port insert; and a passage through said insert adapted to communicate such leakage flow to said high pressure inlet portion. 4. In a fluid pressure system, a pump comprising: a housing having a reservoir cavity and a pump cavity; a pressure responsive member in said reservoir cavity forming first and second variable volume chambers therein; a variable discharge rota-ting piston pump in said pump cavity including,

(a) a shaft rotatably supported by said housing,

(b) a rotor affixed to said shaft, said rotor having a plurality of chambers therein, 1

(c) a plurality of pistons slidably mounted in said chambers,

( d) a control means for varying the stroke of said pistons,

' (e) a pressure responsive means for positioning said control means in accordance .with the pressure developed in said chambers, and

(f) a port insert fixed to said housing and sealingly abutting said rotor, which insert is constructed to have,

(1) a two-stage inlet means with a high pressure portion and a low pressure portion,

(2) a discharge means with pressure transition openings,

(3) an annular chamber surrounding said inlet and discharge means adjacent the abutment with said rotor,

(4) radial passages communicating said annular chamber to said pump cavity, and

(5) a passage through said insert communicating said pump cavity with said high pressure portion of said inlet means,

g) a discharge port in said housing communicated with said discharge means of said port insert,

(h) a high pressure port in said housing communicated with said high pressure inlet portion of said port insert, and

6 (i) a low pressure port in said housing communicated with said low pressure inlet portion of said port insert.

5. In a fluid pressure system a pump in accordance with claim 4 and further comprising:

a first conduit connected to said discharge port; a fluid pressure means connected to said first conduit; a second conduit connected to said fluid pressure means and said high pressure port to return fluid to said P p; a pressure regulating valve operatively connected to said second conduit and to said first variable volume chamber in said reservoir cavity; and a third conduit connecting said first variable volume chamber to said low pressure inlet port. 6. In a fluid pressure system a pump according to claim 4 and further comprising-a compressible means in said second variable volume chamber of said pump reservoir cavity to maintain a predetermined force on said pressure responsive member to control said first variable volume chamber. I

7. In a fluid pressurizing system a pump in accordance with claim 5 and further comprising valve means to control said pressure responsive means positioning said pump control means, said valve means including:

a pressure responsive servo valve operatively connected to said first conduit to control communication of discharge pressure to said pressure responsive means; and

a depressuring valve operatively connected to said first conduit and to said servo valve, which depressuring valve is remotely controlled to move said servo valve to a position scheduling maximum delivery pressure for said pump.

References Cited by the Examiner UNITED STATES PATENTS 2,301,496 11/ 1942 Aldrich 103--2 MARK NEWMAN, Primary Examiner.

W. J. KRAUSS, Assistant Examiner. 

1. A MEANS TO PRESSURIZE AN INLET OF A PUMP TO ELIMINATE NEED FOR A BOOST PUMP IN A FLUID CONTROLLED SYSTEM, SAID MEANS COMPRISING: A FLUID PRESSURIZING MEANS HAVING A FLUID DELIVERY MEANS INCLUDING, (A) A TWO-STAGE INLET HAVING A HIGH PRESSURE PORTION AND A LOW PRESSURE PORTION, AND (B) A FLUID PRESSURE DISCHARGE PORT; A RESERVOIR IN FLUID COMMUNICATION WITH SAID LOW PRESSURE INLET PORTION; A DEVICE TO BE OPERATED BY SAID FLUID PRESSURIZING MEANS WHICH DEVICE IS IN FLUID COMMUNICATION WTH THE DISCHARGE PORT; A CONDUIT FOR RETURNING FLUID FROM SAID DEVICE OPERATED BY SAID FLUID PRESSURIZNG MEANS, WHICH CONDUIT IS CONNECTED TO SAID HIGH PRESSURE INLET PORT; AND A PRESSURE REGULATING MEANS IN SAID CONDUIT TO BY-PASS FLUID FROM SAID CONDUIT TO SAID RESERVOIR TO WHICH SAID PRESSURE REGULATING MEANS IS CONNECTED. 